Centralized traffic controlling system for railroads



June 8, 1937. D. F. DE LONG CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Aug. 29, 193e 2 Sheets-Sheet 1 E NN l E um Q, MT1@ ITL NQJL .n Ew N oz R VJ 1 .lb mw n@ NN S @m mw .Hmmm Il q n EASI. N |l wm .E bm +V .E .0,6 :2 5 2. +N\ H .Av

NVE BY M i ATTORNEY `un'e 8, 1937. D. F. DE LONG CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS 2 sheets-sneek 2 FiLed AAug. 29, 195e Patented June 8, 1937 riss AT t..

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Application August 29, 1936, Serial No. 98,611

14 Claims.

This invention relates to centralized traffic controlling systems for railroads and it more particularly pertains to a means for registering controls in a communication system of the multiple impulse or code type.

In the multiple impulse or code type communication system commonly employed in centralized trafc control systems for the purpose of governing the operation of switches and signals at a distant-held station from a central control oflice, the controls for governing the operation of the switches and signals are transmitted `by a series oi time spaced positive or negative impulses, or impulses otherwise characterized by variable d line circuit conditions or the like. These characteristic control impulses are employed to condition suitable relays at the eld station for governing the operation of pov/er operated track switches and for governing operation of their associated signals.

In one arrangement, such as disclosed for eX- arnple in the prior application of Preston et al. Ser. No. 455,304., filed May 24, 1930, corresponding to Australian Patent No. 1501 of 1931, the character of the control impulse for each step is registered by operating a two-position polarized relay to one position or the other, the armature of this relay, conveniently termed a mag-stick relay, being magnetically held in the position to which it is set until changed by some subsequent impulse. in such an arrangement a control impulse which is for the purpose of operating the mag-stick relay from its existing position to another desired.

position may not be effective, due to a broken wire, a bad connection or the like, with the result that the desired control actually transmitted and received at the field station is not properly registered. Although the system for controlling the switches and signals is so organized that no unsafe condition is produced by such failure, trains may be signalled to advance over a route not desired by the operator.

Another arrangement for registering control impulses is disclosed in the prior application of R. F. Wells, Ser. No. 634,370, filed September 22, 1932, in which neutral decoding relays, all deenerglzed at the beginning of a transmitting cycle, are selectively energized in accordance with One object of this invention is to provide means for registering the code character of the control impulses, which is reliable in its operation but does not require the use of such additional decoding means for each step. 5

Generally speaking, by way of explanation and Without attempting to dene the nature or scope of the present invention, it is proposed to employ neutral stick control relays directly responding in succession to the code character of the control impulses for the successive steps, these relays individually or` jointly controlling the operation of the switches and signals; and to so control these control relays that they are normally deenergized, being selectively energized by the received code impulses by means of their pickup circuits and having their pick-up and stick circuits so arranged that adequate Wrong route protection is provided.

Other characteristic features and advantages of the organization of relays and circuits constituting the present invention will be in part apparent and in part pointed out as the description progresses.

The present invention relates to only a part of a complete system of code communication for centralized traffic control. While it is contemplated that the invention will be used with the various features commonly employed or suitable for such a complete communication system, such as station selection, transmission of indications and the like, in order to simplify the disclosure and `the explanation of the present invention, such features of the complete system are not illustrated and will not be described, except in a general Way and insofar as appears to be necessary to understand the functions and mode of operation of the parts and circuits constituting this particular improvement.

In the accompanying drawings, Figs. 1 and 1A,- With Fig, lA placed to the right oi Fig. l and with correspondingly identified lines in alignment, diagrammatically illustrate the circuit arrangement of the present invention. For the purpose of simplifying the drawings and facilitating in the explanation the various relays and cir- 45 cuits have been shown diagrammatically and conventionally and the symbols and have been employed to indicate connections to the opposite terminals of a battery or other suitable source of currenty instead of showing all of the 50 wiring connections that would be employed in practice.

Referring to Fig. 1, the central control oice of the system is indicated by means of the dotted rectangle in the upper left-hand corner. The code transmitting and code receiving equipment in the control oice is connected to the equipment at the various field stations by three line wires, comprising a stepping and control line Wire I0, an indication line wire I2, and a common return wire I4. The stepping and control line wire Ill, together with common return wire Ill, constitutes a stepping and control line circuit which is energized in the control oce with a series of impulses of selected polarity for operating stepping relays at the field station sequentially one at a time and for conditioning control relays at the station for governing the operation of switches, signals and the like.

For the purpose of explaining and understanding the purpose of the present improvement, it is considered unnecessary to illustrate the code transmitting equipment in the control ofce, by

means of which these series of impulses are applied to the stepping and control line circuit in accordance with the code call for the selection of a particular station and in accordance with the controls to be transmitted, as determined by the 5 positions of switch and signal levers manually set by the operator for the purpose of controlling the operation of corresponding switch machines and signals.

' It is contemplated that the controls for a power operated switch or switches and associated signals will be transmitted as a group to each of the various stations, one station at a time as the operator positions the switch and signal levers for these stations and actuates corresponding starting buttons, all in the manner disclosed in the above-mentioned application of Preston et al. Ser. No. 455,304, or in the manner disclosed in the prior application of Bushnell et al., Ser. No. 640,062 iiled October 28, 1932, corresponding to British Patent 419,399.

It is further contemplated that the controls for a plurality of switches or for various routes may be transmitted, either simultaneously during the same operating cycle or successively on different operating cycles as best adapted to the particular track layout. For the purpose of explaining the nature of the prese-nt invention, vthe various ways of transmitting controls to several control stations for Various track layouts may be disregarded and for the purpose of a sufcient understanding of the present invention it is sufficient to consider that it is applied to a single switch and its associated signals at one field location.

The transmission of indications, station selection, the arrangement and groups of switch and signal controls and other features characteristic of a complete system incorporating the present improvement will be disregarded and this improvement will be considered in its simplest form. Accordingly, included in the eld station apparatus is a three-position biased to neutral polar line relay F connected in the stepping and control line I0. A neutral repeater line relay FP is energized each time line relay F is energized, irrespective of the polarity of energization of re- `lay F, by means of an obvious circuit completed by contact II. A slow-release relay SAis energized over an obvious circuit, including front Contact I3 of relay FP, at the beginning of each operating cycle and is maintained energized during such cycle while line relay F and its repeater relay FP are intermittently operated.

A bank of stepping relays IV, 2V, 3V, etc., and

including a half-step relay VP, is provided at the eld station for marking off the steps of an operating cycle and although the circuits of these relays are not shown in detail it will be understood that they are operated by the intermittent operation of Contact I3 by means of circuits completed through front contacts of relay SA as illustrated by contact I5. Any suitable arrangement of stepping relays may be employed, the particular bank illustrated being assumed to correspond to that disclosed in the above-mentioned prior application of Bushnell et al., Ser. No. 640,062. Since the circuit organization and mode of operation of the bank of stepping relays is explained in detail in this prior application and since its specific form constitutes no part of the present invention, it will be sucient to point out generally certain characteristic features in the operation oi the stepping relay bank.

During the conditioning period at the beginning of a cycle, relays F, FP, and SA are picked up, followed by the picking up of relay VP. Relay VP is maintained energized by a stick circuit completed through back contacts of the stepping relays. When the line circuit is deenergized at the end of the conditioning period and relays F and FP are dropped, the first stepping relay IV is energized, after which it closes a stick circuit for itself which maintains this stepping relay energized until the end of the operating cycle. While relay FP is down, relay VP is maintained energized by an additional stick circuit through a back contact of relay FP. When the line circuit is next energized, relay VP drops since relay IV is now picked up. During the next deenergization of the line circuit, stepping relay 2V is energized through a back contact of relay VP and a iront contact of relay IV; and during the next following energization of the line circuit, relay VP again picks up to prepare the energizing circuit for the next stepping relay SV. This same operation is repeated for as many steps as desired.

Thus, in accordance with the particular arrangement of stepping relays assumed for the specific embodiment of the present invention, after relay VP is initially energized during the first energization of the line circuit in the conditioning period, a stepping relay p-icks up during each succeeding deenergization of the line circuit. Relay VP shifts, that is changes from its energized or deenergize-d condition as the case may be, during each of the succeeding energized periods of the line circuit. This operation of stepping relays IV, 2V, and 3V sequentially establishes local channel. circuits for controlling control relays RA, LA, RD, LD, WN, and WR. in accoi-dance with the polarity of energization of the line relay during the next energized period of the line following the deenergized period during which the corresponding stepping relay was picked up.

The relays illustrated in Fig. 1A comprise lock relay L, lock stick relay LS, signal control relay AGS, normal switch correspondence relay NWCR, reverse switch correspondence relay RWCR, switch position repeating relay WP, track relay T and track repeater relay TP. The operation and cooperation or these relays and their circuits will be brought out in the following detailed clescription.

With the possibility of there being either a positive or a negative impulse for each step, the number of code combinations possible equals two raised to the power of the number of steps. Each one of these combinations may be used for :the

control of the switch and signals .associatedwi-th l-lor lselecte-d at the rst step, 2+ or 2- selected at the second step and 3| or 3- `selected at the third step.

Table of control co'dfejs Third step Second Code number step First step Code use Signal 2B.

Stop SW. re-

verse.

May be used forcall-on signal or the like.

Considering the-general operation of the system, the switch control relays WNand WR are normally deenergized and one or the `other is picked up on the second control step in accordance with the polarity of the impulse received on this step for every control cycle, provided lock relay L is up. The switch control relay which picks up then sticks up from energy applied to the No. l stick bus, includingthe `opposite control relay down, until the end of the cycle when relay SA drops and from then'on until the `switch completes its strokathis latter due to energy applied to the No. l stick bus through a front contact of relay LS which remains picked up until the switch does complete its stroke.

The switch correspondence relay corresponding to the last operated position of the switch is energized and the other correspondence relay is deenergized. These correspondence relays are picked up through .front contacts of the corresponding switch. control `relays and througha neutral and a polar contact of the WP relay in the corresponding position. p `By virtue lof this arrangement, when a route is cleared with the switch in the desired position, no change in position of the correspondence relays takes place. However, if it is desired to operate the switch to the opposite position,` the picking up ofthe .op-- posite switch control relay immediately releases the correspondence relay which is picked up for the opposite position oi the switch and this in turn picks up the LS relay and initiates the move- Ament of the switch. When the switch has complated its movement to the new position, theWP relay assumes a corresponding position and this in turn is followed by the picking up oi the proper switch correspondence relay. This is then followed by the release of the LS relay, which rey moves energy from the switch machine and also removes energy from `the No. 1 stick bus for allowa double impression on the rst step prevents erroneously putting a signal to stop.

It will be noted that the stick windings of the RA and LA relays extend to through back contacts of the WN and WR relays in multiple. This is for the purpose of releasing the RA or the LA relay that was picked up on the first control step, and thus cancel any signal control code, if during a cycle a double impression is received on the second or switch control step.

Signal control relays RD and LD are selectively picked up on the third step, provided that either relay LA or relay RA is still up and that one of the switch control relays' is up. Energy is applied to the pick up windings of the RD and LD relays through iront contacts of the WN and WR relays in multiple to insure that no route can be cleared unless a switch control relay has been picked up toinsure the correct position of the switch as previously mentioned. Either relay RD or relay LD when picked up drops lock relay L because of open back Contact lil or 83, which in turn prevents the picking up of either relay WN or relay WR and with neither WN nor WR picked up no `signal control relay can be picked up to clear the opposing signal.

Front contact 50 oi relay RA is not used, but it will be understood that this contact may be used if desired to pick up another relay for the purpose of giving a call-on signal or the like.

Considering now the sequence of operations and assuming that the last switch control code was positive (2+) for energizing relay WN to cause the switch machine to assume its normal position, relay NWCR was pickedup as a result of the switch machine moving to its normal position .and it remains stuck up over a circuit extending from front contact iii of relay WP, contact il of relay WP in its left hand position, conductor I8, back contact I9 of relay WR, conductor 38, front contact 2i! and winding of relay NWCRto Relay TP is normally energized over an obvious circuit closed at front contact 2i `of relay T, since it is assumed that the illustrated track section is unoccupied `and that relay T is up. Relay AGS is `normally energized over a circuit which may be traced from (-1-), back contacts 22 and 23 of relays RD and LD respectively, conductor 93,

winding of relay AGS and front contact 2li of re-` lay TP, to i The various routes 4set up and the operation which result from the reception of each code in the above code table (except the first and third which are not used) may be best understood by considering each code combination individually. During the conditioning period, relays F, FP, SA, and VP are picked up and when relays E' and l?? `are dropped, following the conditioning period, stepping relay lV is picked up. As previously pointed out the remaining stepping relays are picked up during the successive deenergized periods of the line circuit which follow each impulse, so that the polarity of the next impulse is effective to condition the control relays for that step.

Code N o. 2.-'I'his is the code for clearing signal l A and for actuating the track switch to its normal position. The impulse on the first step is effective to position the polar contacts oi relay F to the right for closing a pick-up circuit for relay RA which extends from (-l-), Contact of relay F in its right-hand `dotted position, back contacts 2.6 and 2l of relays 3V and 2V respectively, front contact 28 of relay EV, bus I+, back Cal contact 29 of relay LA and upper winding of relay RA, to Relay RA opens the pick-up circuit of relay LA at back contact 3l) to prevent the erroneous picking up of relay LA in the event of a double impression of the iirst code. Relay RA closes a stick circuit for itself which extends from (-l-), iront contact 3I of relay SA, front contact 32 and lower winding of relay RA and either back contact 33 of relay WN or back contact 35 of relay WR, to f The second impulse of this code combination is which picks up relay WN over a circuit which may be traced from contact 25 of `relay F in its right-hand dotted position, back contact2l'3 of relay 3V, front contact 2l of relay 2V, bus 2+, lower winding of relay WN, conductor 95, and front contact 35 of relay L, to Relay WN closes a stickk circuit for itself which extends from front contact 35 of relay SA, No. l stick bus, back contact 3l of relay WR, front contact 38 and upper winding of relay WN, to

The picking up of relay WN closes a circuit for operating the switch machine and the associated track switch to its normal position (if not already in this position) which extends from (-i-), front contact 35 of relay WN, normal conductor N,

front contact l5 of relay LS (picked up for reasons to be described), switch machine operating winding, front contact ill of relay LS, reverse conductor R and back contact (i2 of relay WR, to

Relay LS is picked up in response to the` picking up of relay WN (if the switch machine was in its reverse position), because relay NWCR would be down under this condition and relay RWCR would be dropped because of'open back ,contacts 3 and M of relay WN. The pick-up circuit for relay LS extends from front contact IE5 of relay TP, back contacts t6 and 4l of relays RWCR and NWCR respectively, winding of relay LS and front contact 48Y of relay L, to As previously mentioned, relay LS in its picked up position applies energy to the No. l stick bus over an obvious circuit closed .at its front contact lli). When the switch machine and associated track switch attain the normal locked condition, relay WP will be picked up (being deenergized while the switch machine is in operation) and its polar contacts will be positioned to the left.

A circuit is now closed for picking up relay NWCR which extends from (-1-), front contact 5I of relay WN, back contact 52 of relay WR,

, conductor 53, front contact 54 of relay WP, conleffective to pick up relay RD over a circuit extending from Contact 25 of relay F in its left-hand dotted position, front Contact 55 of relay 3V, bus 3 back contact 59 of relay LA, front contact 55 of relay RA, upper winding of relay RD and front contact 6I of relay WN, to

( Relay RD closes a stick circuit for itself which extends from (-1-), front contact @2 of relay T, conductor 63, back contact Sli of relay LD, back contact 55 of relay LA, front contact 56 and lower winding of relay RD, to

Signal IA iscleared over 'a circuit extending from'({), front contact 6l of relay AGS, back contact 68 of relay LS, (which contact prevents the clearing of any signal until the switch reaches the desired position as indicated by the proper 'correspondence relay being picked up), back contact 69 ofrelay L (relay L being dropped when relay RD opens its back contact lll), conductor 1I, back contact 'I2 of relay LD, front contact 'I3 of relay RD, conductor 74, back contact l5 of relay RWCR, front contact 16 of relay NWCR, to the IA signal circuit. Although the detailed circuits leading to signals IA, IB, 2A, and 2B are not shown, it will be understood that these circuits may include such other selections and local circuit protection as desired.

Code No. 4.-The first (-i-). impulse received in this code combination is effective to pick up relay RA`in the manner described in connection with code No. 2. The second impulse picks up relay WR (instead of relay WN), over a circuit extending from (-l-), contact 25 of relay F in its left-hand dotted position, back contact 5S of relay 3V, front contact 57 of relay 2V, bus 2 lowerr windingof relay WR, conductor 95 and front contact 35 of relay L, to Relay WR is stuck up over an obvious circuit including its vfront contact 3l and back contact 38 of relay picked up Whenthe switch reaches its reverse locked positiony over a circuit extending from (-1-), contact 55 of relay WP in its right-hand dotted position, front contact 54 of relay WP, conductor 55, front contactA 52 of relay WR, back contact t3 of relay WN, conductor 'I'I and winding of relay RWCR, to Relay RWCR is lthen stuck up over a circuit extending from (-l-),

front Contact I5 of relayWP, contact I'I, relay `WP in its right-hand dotted position, conductor 18, back Contact 44 ofrelay WN, conductor 18, front contact 80 and winding of relay RWCR, to The opening of back contact 46 of relay RWCR obviously drops relay LS.

rIfhe third impulse is effective to pick up relay RD in the same manner described in connection with code No. 2. Signal IB is cleared over the previously described circuit, but which now extends through back contact 'E6 of relay NWCR and front contact 'l5 of relay RWCR.

Code No. 5.- The first impulse in this code combination is effective to pick up relay LA over a circuit extending from (-1-), contact 25 of relay F in its left-hand dotted position, back contacts 55 and 5l of relays 3V and 2V respectively, front contact 58 of relay IV, bus I back contact 3 of relay RA and upper winding of relay LA, to Relay LA closes an obvious stick circuit for itself at its front contact I and the opening of back contact 29 prevents the erroneous energization of relay RA on this step in the event of a double impression of impulses.

The second (-l-) impulse of this code combination is effective to pick up relay WN as previously described.

The third (-l-) impulse of this code combination is effective to pick up relay LD over a circuit extending from (-l-), contact 25 of relay F in its right-hand dotted position, front contact 25 of relay 3V, bus 3+, back contact 5D of relay RA,

front contact 82 of relay LA, upper Winding of relay LD and front contact 6i oi relay WN, to

The circuit for clearing signal 2A is now completed and extends from (-1-), iront contact 61 of relay AGS, back contact 68 oi relay LS, back contact 69 of relay L (relay L is deenergizedbecause of open back contact S3 of relay LD), conductor 1l, back contact i3 of relay RD, front contact 'i2 of relay LD, conductor Sil, back contact 85 of relay RWCR and iront contact Si? of relay NWCR to the circuit leading to signal 2A.

Code No. 6.-Ihe i-lrst impulse of this code combination is effective to pick up relay LA as previously described. The second (-1-) impulse of this code combination is effective to pick up relay WN as previously described. This is a stop code and is due to the picking up oi relay RA (with relay LA also picked up) in response to the third impulse, by means of a circuit extending from (-1-) contact 25 or" relay F in its left-hand dotted position, front contact 56 of relay 3V, bus 3 front contact 59 of relay LA and upper winding oi relay RA, to (-1-) energy on the No. 2 stick bus is effective to stick up both relays LA and RA and because both back contacts G5 and 8l are ope-n, the stick circuit for the RD and LD relays is incomplete so that both of these relays Will be deenergized. With relays RD and LD both down 'the circuit is complete (including conductor 88) for picking up relay L, which prevents the clearing ofl any signal, due to open back contact 69. Also, since both contacts 'i2 and i3 of relays. LD and RD, respecr tively, are connected to conductor i i, neither bus 'ifi nor Eil can be energized for clearing any of the signals.

Code No. 7.-'Ihe rst impulse ci this code combination is effective to pick up relay LA as previously described. The second impulse of this code combination is effective to pick up relay WR as previously described. The third impulse of this combination is effective to pick up relay LD as previously described, except in this instance is connected to the upper Winding of the LD relay at front contact 89 of relay WR instead of at front contact iii of "relay WN.

Signal 2B is cleared over a circuit extending from front contact Si of relay AGS, back contact 68 of relay LS, back contact @il oi relay L, conductor il, back contact iii of relay RD, front contact 'i2 of relay LD, conductor 3&5, back contact 86 of relay NWCR, and front contact 85 of relay RWCR to the 2B signal circuit. d i

Code No. 8.--The rst impulse of this code combination is effective to pick up relay LA as previously described. The second impulse of this code combination is eiective to pick up relay WR as previously described. The third impulse is effective to pick up relay RA over the circuit previously described. This is also a stop code because relays LA and RA are both picked up. `Both relays RA and LA are stuck up by means of the energy applied to the No. 2 stick bus, and because both contacts E55 and 8l are open, neither relay RD nor relay LD can be energized so that no signal can be cleared.

When the train passes onto the illustrated track section, relays T and TP drop in sequence. The opening of contact 9i of relay TP maintains the L relay deenergized as long as the track is occupied. The opening of contact 24 of relay TP maintains relay AGS deenergized as long as the track section is occupied to prevent clearing any of the signals, because of open front contact 61 of relay AGS. 'I'he opening of front contact 45 of relay TP maintains relay LS deenergized so that the position of the track switch cannot be changed as long as the illustrated track section is occupied. The opening of front contact 62 of relayT deenergizes the stick circuits for the RD and LD relays, so thatl the particular one of these relays which is picked up ist deenergized, and the subsequent closure of back contact S2 of relay TP again applies (-1-) energy to conductor 63, so that relay RD or relay LD can be stuck up in the event that a subsequent code is received while the track section is occupied, so that this subsequent code can be` stored.

In the above description the return to normal or the clearing out function of the system has not been considered but only the complete control operation has been outlined. After the last step has been taken the control line circuit is deenergized in the control olice for a prolonged period of time, so that relays F and FP remain down long enough to allow relay SA to be dropped. The dropping of relay SA effects the deenergization of the stepping relays. The opening of `iront contact 36 of relay SA removes energy from the No. l stick bus and with relay LS deenergized the stick circuits for the WN and WR control relays are deenergized, so that theparticular one of these control relays which was picked up during the cycle is dropped out at the end of the cycle. The opening of iront contact 3l of relay SA likewise removes energy from the No. 2 stick bus, so that the RA and LA relays are deenergized at the end of the cycle.

Stick contact Si) on relay AGS is for the purpose of maintaining relay AGS energized as long as the track section is unoccupied, even though the pick-up circuit of this relay is opened at back contact 22 of relay RD or back contact 23 of relay LD. This maintains the signal clearing circuit complete at front contact 61 of relay AGS. When relay AGS is once dropped, due to the opening of front contact 24 of relay TP, it then requires relays RD and LD deenergized and relay TP picked up for the reenergization of relay AGS.

Having thus described a centralized tralc controlling system as one specic embodiment, it is desired tobe understood that this form is selected to facilitate in the disclosure of the invention rather-than to limit the number of forms which it may assume and it is further to be understood that various modifications, adaptations and alterations may be applied to the specic form shown to meet the requirements of practice without inV any manner departingfrom the spirit or scope of the invention except as limited by the appended claims.

What I claim isz- 1. In a centralized traino controlling system for governing signals associated with a track section located at a field station remote from a control oice, a single stepping and control line circuit extending from the oce to the station and energized with a plurality lof polar impulses, apparatus at the station comprising, a series of stepping relays operated sequentially in response to the energization and ldeenergjzation of said line circuit irrespective of the polarity of such energization, a rst pair of signal control relays each governing the clearing of either of two signals for one particular directionV over a track switch in accordance with its position, a second pair of signal control relays, means governed by said stepping relays for momentarily energizing y one or the other of said first pair of signal control relays at one step depending upon the polarity of the impulse applied to said line circuit for that step, means governed by said Vstepping relays for momentarily energizing one or the other of said second pair of signal control relays at another step depending upon the polarity oi the impulse applied to said line circuit for that step, stick circuits for maintaining said rst and said second pair of signal control relays energized, means including a track relay of a track circuit adjacent said track switch for breaking the stick circuit of said rst pair of signal control relays whereby they are deenergized upon the occupancy of said section, and means controlled by said second pair of' signal control relays for breaking the stick circuit of saidv rst pair of signal control relays whereby said rst pair ofsignal control relays cannot be maintained energized when both of Said second pair of signal control relays are energized.

2. In a centralized trafc controlling system for governing signals associated with a track section located at a field station remote fromy a control office, a control line circuit extending from the office tothe station and energized with a plurality of polar impulses, a rst pair of neutral stick control relays respectively governing the clearing of signals in opposite directions over said track section,a second pair of neutral stick control relays, means for momentarily energizing one or the other of said first pair of control relays depending upon the polarity of the impulse applied to said line circuit at one particular time, means for momentarily energizing one or the other of said second pair of control relays depending upon the polarity of the impulse applied to said line circuit at another particular time, a stick circuit for each of said first pair of control relays including the back contact of the other, and means including back contacts of said second pair of control relays in multiple for controlling the continuity of the stick circuits of said rst pair of control relays.

` 3. In a centralized trailic controlling system of the multiple impulse type, a track switch and associated signals, a control line circuit, stepping relays operated sequentially in response to a series of pol'ar impulses applied to said line circuit irrespective of their polarity, a signal control relay, means governed in accordance with the polarity of one particular impulse of said series at one particular step of said stepping relays for momentarily energizing saidsignal control relay, a stick circuit `for said signal control relay for maintaining it energized after once momentarily energized, means controlled by a detector track circuit for breaking said stick circuit to .deenergize said signal control relay upon passage of a train, and additional means controlled by impulses in said line circuit at another step of said stepping relays for breaking said stick circuit to deenergize said signal control relay.

4. In a centralized traic controlling system of themultipleimpulse type, a track switch and as- 'sociated signals, a control line circuit, stepping relays operated sequentially in response to a series of polar impulses applied to said line circuit irrespective oitlieir polarity, two neutral `signal control relays, means governed Vin accordance with the polarity of one particular impulse of said series at one particular step of said stepping relays rforv momentarily and selectively energizing one of said signal control relays, stick circuits for A signal said signal control relays for maintaining them energized after once momentarily energized, means controlled by a detector track circuit for breaking said stick circuits to deenergize said signal control relays upon passage of a train, and additional means controlled by impulses in said line circuit at another step of said stepping relays for breaking sai-d stick circuits to deenergize said signal control relays.

5. In a centralized traffic controlling system for railroads comprising an oiiice and a station, means at said station ior receiving a series of current impulses transmitted from said oflice, a track switch and a pair of switch control relays at said station, means responsive to the reception of certain of said impulses for selectively energizing one or the other of said pair of switch control relays, means controlled by the energization of said one or said other of said switch control relays ior operating said track switch to normal or reverse positions respectively, a pair of opposing signals governing traflic over said switch, a rst and a second pair of signal control relays at said station, a control circuit for each signal closed only when the corresponding relay of said rst pair of signal control relays is energized, means eiective when selected impulses are included in said series for energizing a selected relay of said first and said second pair of signal control relays, means operated by each relay of said pair of switch control relays for releasing the other relay oi this pair, means operated by each relay of said iirst pair of signal control relays for releasing' the other relay of this pair, and means operated by both relays of said second pair of signal control relays for releasing either or both relays of said rst pair of signal control relays.

6. In combination with a railway switch; four signals for governing traic over said switch; two switch control relays; means for operating said switch to one position or the other according as one or the other of said switch control relays is energized; a plurality of signal control relays; means controlled from a remote point for selecting said switch and said signal control relays; four signal circuits, one for each of said signals and each including contacts closed only when the route over the switch governed by the associated operated by each of said switch control relays when energized for completing energizing circuits for one portion of the selected signal control relays; and means operated by each of said switch control relays when deenergized for completing energizing circuits for another portion of the selected signal control relays.

'7. In combination with a railway switch; four signals for governing traic over said switch; two switch control relays; means for operating said switch to one position or the other according as one or the other of said switch control relays is energized; a plurality of signal control relays; means controlled from a remote point for selecting said switch and said signal control relays; four signal circuits, one for each of said signals and each including contacts closed only when the route over the switch governed by the associated signal is available and unoccupied; means operated by each of said switch control relays when energized for completing energizing circuits for one portion of the selected signal control relays; means operated by each of said switch control relays when deenergized for completing energizing circuits for another portion of the seis available and unoccupied; means i lected signal control relays; and stick circuits for each signal control relay of said one portion controlled through back contacts of another signal control relay of said one portion.

8. In combination, a line circuit having a plurality of coded impulses applied thereto, a track switch, a signal for governing traiiic over said track switch, a signal circuit for said signal, a switch control relay actuated by one of said coded impulses for governing said track switch, a correspondence relay, means controlled by said coded impulses for selecting said signal circuit, a correspondence relay, means controlled by said track switch and said switch control relay in corresponding positions for completing a pick-up circuit for said correspondence relay, means controlled by said track switch and said correspondence relay for completing a stick circuit for said correspondence relay, and means controlled by said correspondence relay for completing the Selected circuit for said signal.

9. In combination, a line circuit having a plurality of coded impulses applied thereto, a track switch, signals for governing traino over` said track switch, signal circuits for said signals, a switch control relay actuated by one of said coded impulses for governing said track switch, signal control relays actuated by other or said coded impulses for selecting said signal circuits, a correspondence relay, means controlled by said track switch and said switch control relay in corresponding positions for completing a pick-up circuit for said correspondence relay, means controlled by said track switch and said correspondence relay for completing a stick circuit for said correspondence relay, and means controlled by said correspondence relay for completing the selected circuits for said signals.

10. In combination, a line circuit having a plurality of coded impulses applied thereto, a track switch, signals for governing traic over said track switch, signal circuits for said signals, a plurality of switch control relays actuated by certain of said coded impulses for governing said track switch, signal control relays actuated by other of said coded impulses for selecting said signal circuits, a plurality of correspondence relays, means controlled by said track switch and said switch control relays in corresponding positions for selectively completing pick-up circuits for said correspondence relays, means controlled by said track switch and said correspondence relays for completing stick circuits for said correspondence relays, and means controlled by said correspondence relays for completing the selected circuits for said signals.

1l. In combination, a line circuit having a plurality of coded impulses applied thereto, a track switch, signals for governing trarlic over said track switch, signal circuits for said signals, a plurality of switch control relays actuated by certain of said coded impulses for governing said track switch, signal control relays actuated by other of said coded impulses for selecting said signal circuits, a plurality of corresponding relays, means controlled by said track switch and said switch control relays in corresponding positions for selectively completing pick-up circuits for said correspondence relays, means controlled by said track switch and said correspondence relays for completing stick circuits for said correspondence 12. In combination, a line circuit having a series.

of polar impulses forming a code transmitted thereover, a polar relay included in said line circuit ior repeating said impulses, step-by-step mechanism operable to take one step for each of said impulses, a rst pair of control relays and a second pair of control relays, circuits for said first pair of control relays prepared at one step of said mechanism and selectively energized in accordance with the polarity of the impulse transmitted at that step as repeated by said polar relay, and circuits for said second pair of control relays prepared at another step of said mechanism and selectively energized in accordance with the polarity of the impulse transmitted at that step as repeated by said polar relay only when one of said iirst pair of relays is energized and the other is deenergized.

13b In combination, a line circuit having a series of polar impulses forming a code transmitted thereover, a polar relay included in said line circuit for repeating said impulses, step-by-step mechanism operable to take one step for each of said impulses, a rst pair of control relays .and a second pair or control relays, circuits for said first pair of control relays prepared at one step of said mechanism and selectively energized in accordance with the polarity of the impulse transmitted at that step as repeated by said polar relay, circuits for said second pair of control relays prepared at another step of said mechanism and selectively energized in accordance with the polarity of the impulse transmitted at that step as repeated by said polar relay only when one of said rst pair of relays is energized and the other is deenergized, and stick circuits for said second pair of control relays completed when and only when one or the other of said rst pair of control relays is deenergized.

14. In combination, a line circuit having a series of polar impulses forming a code transmitted thereover, a polar relay included in said line circuit for repeating said impulses, stepby-step mechanism operable to take one step for each of said impulses, a rst pair of control relays and a second pair of control relays, circuits for said first pair of 'control relays prepared at one step of said mechanism and selectively enel'- gized in accordance with polarity of the impulse transmitted at that step as repeated by said polar relay, circuits for said second pair or" control relays prepared at another step of said mechanism and selectively energized in accordance with the polarity of the impulse transmitted at that step as repeated by said polar relay only when one of said first pair of relays is energized and the other is deenergized, stick circuits for said second pair of control relays completed when and only when one or the other of said rst pair of control relays is deenergized, and means for sticking an energized one of said rst pair of control relays as long as a series of impulses is being transmitted over said line circuit.

DARROL F. DE LONG. 

